As with any significant change in eating habits, there may be safety issues you need to be mindful about.

In this guide, we break down the information you should be aware of to make sure you get the most out of the ketogenic diet and don't run into trouble.

Any significant change in diet should be discussed with your doctor before starting it. This is particularly important for very-low-carb ketogenic diets.

Pregnant women

Prolonged maternal ketosis has been associated with development problems for the baby which could affect brain development or increase the risk of neural tube defects such as spina bifida.

As the risk of harming the baby from being in ketosis during pregnancy is too high, a ketogenic diet is not recommended by doctors. [236]

Breast feeding women

There is a lack of studies on the safety of ketogenic diets whilst breastfeeding and therefore it is recommended that people maintain a conservative carbohydrate intake rather than going for a very-low carb intake.

The thinking here is, we don’t know what the result of a ketogenic diet on breastfeeding is so adopt a moderate carb intake as we know that it is safe.

People on hypo-causing medication

This is because these medications are all designed to increase insulin in the body, which lowers blood sugar levels.

Following a low-carbohydrate ketogenic diet whilst on these medications can increase the risk of hypos and so it is very important that you speak with your doctor to take precautions against hypos before you start a ketogenic diet.

Regular blood glucose tests will help you to spot and avoid hypos. It is advisable to test more often than normal whilst you are adjusting to a change in carbohydrate intake.

People on other medication

Other diabetes medication should not pose a significant risk on the diet but may need to be reviewed to ensure it is still appropriate and needed.

Your doctor will advise you if any changes to your medication or doses are needed.

Blood pressure medication may also need to be adjusted by your doctor as blood pressure will often drop on a ketogenic diet.

Low to very low BMI

People with a low BMI looking to follow the diet for the non-weight loss benefits (such as improved blood glucose control) will need to prevent weight loss from occurring.

Your doctor or dietitian should be able to help you to take precautions, such as modifying the diet, to ensure your body weight is healthy.

Children

The ketogenic diet has been used safely, with medical supervision, for many years in children for the treatment of seizures.

There are a number of considerations to bear in mind before starting a ketogenic diet including ensuring the balance of macronutrients (carbohydrate, protein and fat) is appropriate for the growth of children.

For this reason, a doctor and dietitian should be consulted before a ketogenic diet is started in children.

Gallstones

People with gallstones used to be advised to avoid fat but this is no longer the case and the NHS now states that very-low-fat diets may actually promote gallstone growth. [237]

If you have gallstones, eating fat may initially lead to some gallstone pain. If you wish to follow a ketogenic diet, you may need to introduce it slowly or go onto the diet once the gallstones have been removed or dissolved.

A review of studies from 2014 shows that high fat diets appear to prevent gallstones formation which suggests a good long-term benefit.

Gallbladder removed

Whilst the gall bladder contains bile, that helps the body to break down dietary fats, some people report that it is possible to follow a low-carb, high fat diet without a gallbladder.

Beachbag is one of our forum members who has been following a low-carb, high-fat diet for a number of years despite having had her gallbladder removed.